Airway traffic control system



April 20, 19 48. N. D. PRESTON ET AL ,439,

' AIRWAY TRAFFIC CONTROL SYSTEM Filed Oct. 11, 1945 .12 Sheets-Sheet 1 POSTING :PANEL FLIGHT No. TIME AL E@ EHEHE@ |E| H E 3K TC ANG ABLE IE [5 m E} INDICATORS I [U E m E E] 51 I E] Elm El i L L L P 1 I AUTOMATIC I LJE Q EEJ sEouE-NcE {PANEL FLIGHT No. TIME ALT. W E El [E] E! m E 2ND 1 [5| CHAN6EABLE l 512]) [2| [5' '1} III E] INDICATORS I 4H m E] E El E I v CONTROL PANEL FLIGHT sc EDuLE SETTING DIALS m 1 F2 DTl m2 DT3 DT4 DA 5 \II' \II' \II" \II" 1'' I II) POST I I I l G- FLIGHT NUMBER IoHIas. HRS. 1OMIN5.. MIN. ALT.

SEQUENCE CONTROL I Q Q WIPE-OUT CONTROL 15L 25L sea 50K D1 D2 INDICATION LAMPS AUD%BLE CLEAR'OUT A I NPK PK WOK s L 9E FLIGHT NUMBER W05 INVENTORS' NDPreston ahd FBHitchcock BYWMW-kl,

Their ATTORNEY;

April 20, 1948. N, PRESTON ET AL 2,439,948

AIRWAY TRAFFIC CONTROL SYSTEM Filed 001:. 11, 1945 .12 Sheets-Sheet :s

F (See Fm.

1 57 SEE 262 INVENTOR5 Nggresto'n and F. BHiichcock 'wwmw,

- Their ATTORNEY April 20, 1948. N. D. PRESTON ET AL 2,439,948

AIRWAY TRAFFIC CONTROL SYSTEM Filed 001;. 11, 1945 112 Sheets-Sheet 4 ETTING DIAL5 445 (5:: 56.515) 444 DTZ DT5 DT4 DA FIGuZC \J' 10 MIN.

MIN.

HES ALT.

UNIT

PANEL TYPICAL UNIT PANEL W Hm HI Jil NDPresfon and EB. Hitchcock BUSES 0-1-2 BUSES 0-9 nvsss 05 a Their ATTORNEY A ril 20, 194s. N. D. PRESTON ETAL 2,439,948

AIRWAY TRAFFIC CONTROL SYSTEM Filed Oct. 11, 1945 .12 Sheets-Sheet 6 P s isgg qr FLIGHTNO. DECODER v 55f POSTING N 1 A 51 T12 BUTOR DECODERS 440 I V I I l I A 2ND men FLIGHT NO. 17

3 IO-HOURS t 3 UNIT HOURS A pqgqu 4 45 3 IO-MINUTESIC 4,. ZFUNIT MmuTEs;

38 SEE FrazA I: DECODERJ 42? I i ALTITUDE l i I I A I i 402 A932 1 a); i g 590 3*?1 -wl 4/55 a i 455 4% t(+) i 459 415' 427 .555 556 INVENTORS NDPresEon and FfiHl'Tchcock Their ATTORNEY April 20, 1948. N. D. PRESTON ET AL 2,439,948 I AIRWAY TRAFFI CONTROL SYSTEM Filqd Oct. 11, 1945 12 Sheets-Sheet 7 mf av LERINTEIZ WIPE-OUT REPEIBF 'ORATOR 555 INVENTORS Nlg Prcstoh and EB. Hitchcock Mam,

- Their ATTORNEY April 20, 1948; N. D. PRESTON ET AL AIRWAY TRAFFIC CONTROL SYSTEM .12 Sheets-Sheet 8 FilGd 0013. 11, 1945 v H Flehb. ROUTE TYPICAL WIPEOUT MESSAGE PQINT CHARACTER (SEE F 16 2A) C m il 3% d QM .mv 4m m P D..B N

Their ATTORNEY April 0, 1948. N. D. PRESTON ET AL 2,439,948

AIRWAYJTRA FFIC CONTROL SYSTEM I Filed Oct. 11, 1945 ,12 Sheets-Sheet 9 F SEQUENCE DIAGRAMS TYPICAL MANUAL POSTING OPERATION SET DIALS FOR FLIGHT DATA-ACTUATE PB @913 T E5T FOP SAME FLIGHTNUMBER FCRi FPB 5L W122 IF SAME FLIGHT NUMBER r v POSTING F V lTCPl, TRC'Z, TRC5, TRC4; ACR FIG- 6B.

TYPICAL MANUAL WIPE-OUT OPERATION SET FLIGHT NO. ACTUATE BUTTON WOB M015 1 WOR W51??? i?! j gcpwcnz, rczagrcrez, Tans, TCR4,ACR yep 1-FV FIG. 6C.

"rg cAL SEQUENCING OPERATION }5ET H125. RIC. PICJ lsET UNITHOURS 5521K; v

SETIOMINS. fI ET c a T}5ET UNIT MINS.

' 55 1: t u INVENTORS I E wc SELECT NEXT SELECTOR I TIME ND Preston and FBHdchcock STEPPING I F BY l MAGNET PSET C 9 6124 A "E5557 Their ATTORNEY p '20,1948. N. D. PRE\STON ETAL 2,439,948

AIRWAY TRAFFIC CONTROL SYSTEM NDPresto'n and EB. Hitchcock Their ATTORNEY April 20, 1948. N. D. PRESTON ETAL AIRWAY TRAFFIC CONTROL SYSTEM Filed 001:. 11, 1945 .12 Sheets-Sheet 12 ssi n au ojom mzthou mom 2 NEE E588 Qz @525 E5 zowzmmmo .Somfi? mat/FEE. 36E:

INVENTORS NDPreston and FBHitchcock Their ATTORNEY Patented Apr. 20, 1948 UNITED STATES PATENT OFFICE Neil D. Preston and Fore st B. Hitchcock, Rochester, N. Y., assignors to General Railway Signal Company, Rochester, N. Y.

Application October 11, 1945, Serial No. 621,778

This invention relates to airway traffic control systems, and more particularly to an organization for posting and displaying data for scheduled flights in a suitable panel in the particular chronological order or sequence of their scheduled times.

The system of the present invention involves features of controlling a posting panel which may be considered as improvements over similar features in our prior application Ser. No, 528,926 filed March 31, 1944; and no claim is intended to be made in this application to subject matter common with such prior application. Furthermore, the complete organization contemplated in said prior application Ser, No. 523,926 also included features pertaining to the reception and decoding of Teletype messages similar to those disclosed in this application; but, it is to be understood that claims to such subcombinations are made in our continuing application Ser. No, 5,694

filed February 2, 1948.

The primary purpose or object of the present invention is to provide a system organization for posting or storing the data for a number of flight schedules as and when'such data becomes available, and for automatically sorting out and displaying in a suitable sequence panel the data for a number of such flights in the strict time sequence or chronological order of their scheduled times.

Generally speaking, and without attempting to define the nature and scope of the invention, it

is proposed to provide a posting panel on which electrically operable changeable indicators in different rowsor posting spaces may be set automatically in response to a manual control or messages received over Teletype facilities so as to display the desired data for scheduled flights, such as flight number identification, scheduled time, altitude and the like. This data for different flight schedules is posted in difierent posting spaces in any order that vacant spaces from one end of the 81 Claims. (Cl. 177353) panel happen to become available to receive such flight data, and independently of the sequence in which previously posted flight data has been posted.

After accumulation and display of the data for various flights in this manner and in an order which does not necessarily correspond with the chronological sequence of their scheduled times, it is proposed to provide an automatic time sorting and posting means, which is set into operation upon each change in the display of flight data in the posting panel either b the addition of data for som additional flight, or by a wipe-out of data for a flight disposed of, or in response to suitable manual control, as the operator may desire, and which acts automatically to sort over all of the flight schedules posted in the posting panel at the time and repost a predetermined number of these flight schedules by the positioning of like changeable indicators in a separate sequence panel in successive spaces from one end in the chronological order or time sequence of the scheduled times, so that the complete data for a desired number of scheduled flights is rearranged in the sequence panel in the order of their scheduled times for the guidance and information of the operator.

The proposed system also includes various other features in connection with this general plan of posting and time sequencing. Whenever posting of a new schedule for a flight is initiated, there is a provision for automatically selecting and revising the schedule for that same flight if already posted in the posting panel, or posting the new schedule in the first vacant space in the posting panel if there has been no prior posting for the same flight. Also, provision is made for automatically selecting and wiping-out the data for any identified flight when that flight is reported as having landed, or has otherwise been disposed of so as to be no longer of interest to the operator. These posting or wipe-out functions may be performed either by manual control, or by automatic control in connection with posting and wipe-out messages punched in a tape in connection with the reception and printing of such messages by the usual Teletype facilities, or like code communication system, I connection with such automatic posting and wipe-out under the control of Teletype messages, special provision is made to check the number of characters in these messages, and reject without any posting or wipe-out operation any message which is defective in the number of its characters. Also, any message including an error or correction code character is rejected by the posting 3 apparatus. The existence of a defective message is automatically brought to the attention of the operator by a suitable alarm which enables him to take the appropriate action to bring about a proper posting or wipe-out operation.

It is also proposed to combine and interlock these various functions and features of operation for a system-of this character i such a way as to perform the various manual or automatic functions in a way to afford a flexible and accurate system for posting and time sequencing flight data.

One important characteristic of the system organization of this invention as a wholeis that the parts and circuits have been especially 'arranged to provide for the positioning of indicators and operation of other movable elements of the system in accordance with the normally closed circuit principle of failure on theside of- For example, in the system of this-invention each of the changeable indicators and the multiple position contacts of the time sorting means is operated to the particular position called for by the energization of a control bus belonging to that position, as distinctive from being operated by a prescribed number of successive impulses that may or may not 'beefiective; and if any indicator or 'contactor involved in an operation should fail to move/or should fail to stop in the proper position due to a broken wire, bad contact,- or the like, the system stalls for that operation, instead of carrying'out-an' erroneous operation. The-operator, realizing that a fault has developed may manually clear out the stalled condition, and also take-such other action in the way of emergency cut out of'--the vacant-space selection, replacement of defective parts, or the like, as may beappropriate.

Various other objects, functions,=--attributes, and characteristic features of the-invention-will be in part apparent and in part pointed out, as the description of a specific embodiment of the invention progresses.

In describing the invent-ionin detail, reference will be made to the accompanying drawings in which the various parts and circuits for one specific embodiment of the invention have been illustrated in a simplified and. diagrammatic manner, more with the object of facilitating an explanation'and understanding of the nature of the invention and its mode of operation, than for the purpose of showing in'detail the construction and'arrangem'entof parts that would be preferably employed in practice. In these drawings, various diagrammatic and conventional representations have been employed. Ihe system includes a number of relays, mostly simple direct current operated neutral relays of the usual type and construction, with anumber'of contact fingers cooperating with make or front 7 contacts, and with break or back contacts in the usual manner. In the interests "of simplifying the showing of circuits, the contact fingers of the various relays have been shown conventionally either below or above the representation ofthe'reother suitable source of current, an operating circuit being established when a conducting path is available from a wire end having and an arrow pointing toward a wire to some other wire end having and an arrow pointing away from thewire. Various other diagrammatic or sche- "mafia-representations on the drawings for the various devices will be explained as the description-progresses. In describing the invention in detail, reference will be made to the accompanying'drawings, in which like reference characters designate corresponding T :part-s' '-throughout' the several'views; and in which:

Fig. 1 is a general view'illustrating thepb'sting and sequence panels, together-"with the manual control board and other apparatus in 'block form;

Figs. ZAf'ZBand 20, when arranged si'de by side, illustrate the organizatiomof parts an'd circuits' for one typical' posting s'pace h'aving: a plurality of changeable indicators" fo'r'the posting panel; another typical 'po'sting space for the sequence panel; and' the associated relays and circuits for f carryingout the posting, wipe-out and time'sequencing functions;

' Figs. 3A to'3D inclusive, when arranged side by side,"-illu'stratef the circuitorganization for receiving and decoding Teletype mess'ages t@ be used with the posting-and wipe-outcircuit 'organization of Figs.'2A to 20;

Figs; 4-"and 5 illustrate the'punching'sin the tape for typical posting and wipe-out messages respectively;

Figsi- 6A to 6B are explanatory diagrams ihdieating generally the sequence of'relay-operations involved in 'ce'rtain'typical' operations "of the system;

' Fig. 7 is afragmentary circuit-diagr'am ill-ustrating certain interconnecting circuits between the indicator' units and relays for 'apl'urality 'of spaces of the posting panel; and

' Fig. B- iIlustrates the; structure of one type' of changeable indicator disclosed in o'ur prioi' appliassumed to .be used for thepar ticular arrarigement' of circuits illustr'ated as 'an' embh'dii'hrit for this invention.

General organization Before discussing in detail 'certaimtypicar'examples of s the contemplated 'operation 'of the system, it will be helpful to 'considergenerallythe nature and 'thecharacterof some-of-the-component parts of the system, and explain some-of their operating characteristics.

Posting paneL- 'Ihe posting panel shown generally in" Fig. 1 comprises asuitable frame-structure for'housing'and' supporting a number 'of horizontal rows of electrically operable changeable indicators; each movable iroman mien or blank position to a selected operated positionyto display by figures'or the like the desired data for a'fiight; Each'of these rowsof indicators, constituting what is conveniently'termed a posting s'pace,'-comprises a plurality ofindicators'suit- 5 able for displaying the desired data. As illustrated, there are two indicators for the two digits of a number for flight identification, four indicators for the four denominations of time of a 24-hour day, and one indicator for altitude; but the organization of circuits may be adapted to any desired number of indicators affording the desired information with respect to a flight.

The posting panel may include any desired number of posting spaces or rows of indicators, as may be considered necessary to provide a display of data for. an adequate number of approaching flights needed for the information and guidance of the operator. The number of posting spaces in the posting panel does not limit the number of posting messages that may be received over the Teletype facilities, because posting messages in excess of the capacity of the panel may be stored in the punched tape record and used when posting spaces become available.

Changeable indicators-The changeable indicators in the posting panel may take any suitable form having multiple position contacts and operating means; but in connection with the particular circuit connections shown, it is assumed that these indicators will be of the self-propelled step-by-step type, such as disclosed in our prior application, Ser. No. 528,926, filed March 31, 1944. This type of changeable indicator, illustrated for convenient reference in Fig. 8, comprises-an indicator drum 5 mounted to turn on a vertical axis and supported by-the lower frame member 6 of the indicator unit. The numbers or other desired symbols on the periphery of this drum 5 are exhibited in its different positions through, an opening I in a suitable mask forming the front plate 8 of the unit. This indicator drum 5 is connected by spur gears 9 and I and beveled gears II and I2 to an operating shaft [3 extending longitudinally 0f the unit, and supported in the end members l4, l5 of the support I6 01 an operating element fastened by screws to the frame member 6. The core I!) of an operating magnet or solenoid OM carries an armature 22 which has a notch cooperating with a fix stop 23 to prevent turning movement of the core. The core I9 is biased to the left by a coil spring 24, and carries two discs 25 and 26 cooperating with toothed collars- 21 and 28 respectively, fixed to the operating shaft l3, so that as the operating magnet OM is energized to attract the armature 22 to the right, the teeth on the disc 25 cooperatewith the teeth on the collar 21 to turn the operating shaft l3 approximately half way to the next position, and upon deenergization 0f the operating magnet 0M, the spring 24 restores the core l9 to the normal position shown and causes the teeth on the other disc 26 to cooperate with the teeth on the other collar 28 to turn the operating shaft l3 to the next active position of the indicator. Thus, as the operating magnet OM is intermittently energized, the operating shaft I3 and the indicator drum 5 are moved step-by-step.

, The number of active indicating positions for each indicator depends upon the data it is intended to display, there being a blank position and ten active positions for the indicators representing the difierent digits of flight number and the unit minutes, and a smaller number of active positions for the indicators representing the tens of hours, hours and tens of minutes. The indicator illustrated in Fig. 8 has a blank position and ten active positions. The number and spacing of the teeth on the discs 25 and 26 and the collars 21 and 28 may be varied to suit the number of active positions of the indicators, or the same indicator may be used in each case with idle movement past unused positions.

Each changeable indicator includes a set of position contacts, which, as shown, comprises contact fingers 32 arrangedaround a cylinder 29 of insulated material like the staves of a barrel and operated from the inside by a roller 30 on an arm fixed to the operating shaft l3. As the indicator drum 5 assiunes its different positions the roller 30 engages a pin 33 on a contact finger 32 for the corresponding position to move that contact finger outwardly against its spring bias.

These contact fingers 32 engage a continuous conducting sleeve 34 secured to the insulated cylinder 29, so as to complete circuits one for each position of the indicator.

The indicators are also provided with emptyfull contacts which comprise a movable finger 38 operated by a roller and arm 36 on the operating sh'aft l3, and moved from one extreme position to the other to engage different stationary contacts 39 and 40 as the indicator is moved into and out of the blank position. In some cases, these empty-full contacts can be omitted.

The indicator unit as a whole is preferably provided with a detachable plug connection for its connectin circuits, as indicated at 29a, so that it may be readily removed from the front panel for replacement purposes.

It may be pointed out here that the same type of step-by-step indicator device is used for the units of the time sorter, with or without indicating drums, as desired.

t is contemplated that these changeable indicators will be operated from a master pulsing bus P which is intermittently energized in a suitable manner, such as by a motor-driven cam 42 operating contacts 43, as shown in Fig. 23, so as to provide the duration and spacing of energization of the operating magnets OM of the various indicators best suited to their rapid and accurate operation. Each changeable indicator is set'into operation and stopped in the selected position by controlling the connection between its operating magnet OM and this master pulsing bus P in a manner more conveniently considered later in discussing the detail operation.

In the circuit diagrams these changeable indicators are shown diagrammatically, with the operating magnet OM in block form, and the position contacts represented as a rotating arm engaging stationary contacts connected to control buses. In reviewing the circuit connections, it should be understood that when the operating magnet OM for any one of the indicators is intermittently energized, the contact arm is assumed to be moved clockwise from its blank vertical position in a step-by-step operation to its different contact positions, until the indicator. has assumed a position corresponding with an energized control bus, in which an associated correspondence relay, such as the relay IFCRI for the first digit of night number in the first posting space in Fig. 2B, is energized to open the circuit for its associated operating magnet 0M and discontinue any further intermittent energization of such operating magnet OM. Since the contacts for each different position of an indicator become closed upon deenergization of its operating magnet OM at the end of a pulse, the associated correspondence relay is immediatelypicked up if that position is connected to an energized bus, thus assuring that the contact arm and associated indicator drum zg' ramees will remain in' such set -position beoause the picking up ofthe-correspondence relayppens the circuit for theassociated--ioperatingmagnet M beiore the next -pulseoccurs; I

- Timesequencing --appa,ra'tus .-T1iesequence panel comprises changeable --indieaitors arranged in rows or posting spaces= the-same as o'rthe posting panel; and is in etfe'ct a supplemental or nadditioiial posting: panel =intoc=whi6h flight data zfrom the posting :pa-nel may b'e reposted in the proper time sequence. Under. ordinary conditions, itis likely --that "-a smaller ":number of posting spacesxin' .the sequence'-.-paneI'- than in the main postingpanel will provide the necessary information 'for-the-operator; 'and for the pur pose :of-illustration it has been assumed that the sequence panel williincludealimited nunibr of:postingzspaces such as -fourt l lbwever; it should be understood-what any suitabIe' number ofiiposting spaces "may be "provided in the-se quence- .zpanel; and-:in some-cases -it vmay be desirabletorhave-the sarn'ecnumber ofspaces in theisequence panel as is provided in the posting panel;

The orderiin which the-postings are: made in the sequence panel in successio'n eitherzircm the top down-as shown, :or from theibottom"up; as may be desired;.is determined bythe opera tionnoi a multiple position ste'ppingacontactor;

conveniently termed iaspace selector, which' -is.

shown diagrammatically :iii Fig} 2A as comprisme, two scontact arms: 1'3 :and 1 35*moved to step. -and ihalf-step positions by a suitable stepping mechanism STM.

The xtime. sorter comprises -'-four :similar multipleie'position'contactor .units, one for each de-- unit minutes denominations of time afor a 24-.

hour.; day; and shown. schematically ,inFig. 20, have been designated for convenience TI-IS, UHS, TMSand Uli/LS, and are connected to andgovernedby .a corresponding group-of time units.

Asidefromthe different number of active positionsrequired ;on account; of the varying number :of. digits in the different denominations of. time eachuof these-units are constructed. and operated in 'the same way, and for convenience are assumed to have the same construction as ach'angeable indicator unit; such as shown-in Fig. 8, with or without the indicating drum, as-

desired.

' Associated with each ofthese time sorter .units, and'functionally forming a part thereof,flis a clearrout relay such as. 00,100, etc., and a timecorrespondence relay, such' as ITC, IZTC etc The functions of these relays and'the'cona trol. circuits involved are more conveniently con sideredlater in discussing typical operations.

Thensystemis illustrated in a conditionsuch that. any posting .or wipe-out operation either manual oruautomatic will initiate a sequencing operation. If desired, however, such.- automatic initiation of 'the sequencing operation eanzzbe stopped at: the will-.01; the-operator. by actuating the: sequence controlilever .lSLotFigs. 1 and 2A:

to :an. operated position. Under such a condition,--the sequencingoperation will take place only when manually initiated by-'the operation*of thesequence"butt'oir-SQB? on the other hand; the-lever- SIS- oan *be le'ft =in: its normal position illustrated and-the lever 2SL 'moved to an ='oper-' ated position thus -causing the sequencing oper-- atio'n to' take place automatically following each wipe-cut operation but not following- -a postin'g operation: Then th'eoperator can allowone or mo-re posting operations 'tooccur before =-he manually initiates the sequencing operation, it being=understood that-theoperator=can,'of course, in'itiate iafisequenci-ng -'-'operationatany time-"by actuating the -btltton SQBZ' During each sequencing operation, regardless offlhow it is in'iti'atedf-the indicator lamp SQK' iS' illuminated-to advise the operator that such a sequencing oper ation is taking place .and-when-.-such operationhas been completedf Posting cmd wipeaout -facilities;-In accordance with this invention; provision 'is' 'made' i for the posting "or' -wip'ing-out of flight: data in the postin'g panelieitherby-.manua-tsetting and controlpor automatically'by Teletypemessages recorded on a punched tapet Either of these postingand-wipe-out-facilities accomplishes the necessary functions; but it is contemplated that-ordinary operating conditions make it desirable toemploy bothmanual and automaticposting 'and wipe-out facilities. For example; when the posting and time sequencing organization .of thisinventi'o'n is usedin connec-' tion with approach controlor landing. procedures, it: *is'slikely that information regarding -certain flights will be communicated to the central ofii'ce,

from zone or-more outlying fix locations at which the approaching flights are observed, by Teletype where Iletype facilities are -available-,-so that it is advantageous irrth interests of saving manual" effort and-avoiding humau errorto utilize such Tletype iacilities to 'make" the posting I and -wipe-' out operationsautomatically; reserving-the man-' ualaiposting and=wipe-out operationfor 'theuse of i the operato'nto take care of other conditions; For these reasons-the organization'of this inven-- tion; .as disclosed comprises suitably '-interlockedmanual T and automatic posting and" -wip'eout faeili'tiesi'- The equipment 'for manual posting comprises suitable manually operable setting dials shown diagrammatically l for =flight number DFIZ 'DRZ, for-*schedziled time*DTI, DTZ', DT3 and -D'I 4, for* altitude DA," and the like, togetherwith I a push button PB for initiating posting "op-5 eration. These setting dial-s are merely representative *ofany suitable iorm' of manually .operable selecting-circuit controllers;- and may 'betkey set=devices 0rthe like." Asshown, separateflight' numbr'setting'dia'ls WDF'I and; WDFZtOgether with a push buttonWOB are employed for the wipe-out operation, *on the-assumption that-sepa rate dials -andinitiatingbutton for' this purpose enablethe wipe-out function to be-performed by a separate operator if so'desired; and also because the--use-of separate flight number .dia-lsfor "per-- forming-the wipeoutfunction'is lesslikely to resultin =carele'ss or wron'g manipulation.

9 The facilities for receiving and decoding Teletype messages for performin the posting and wipe-out operations automatically, as illustrated in Figs. 3A through 3D, comprise a selecting or routing means associated with the conventional Teletype receiver arid distinctly responsive to different codes to route the wipe-out and posting Teletype messages to two separate tape reperforators (i. e. a posting reperforator and a wipe-out reperforator), so that the postin and wipe-out messages are punched in separate tapes, thereby permitting the use of the Wipe-out messages at any time independently of the number of preceding posting messages. Thus, even though the posting panel is full, and additional posting messages may have been received and stored in the tape, the reception of a wipe-out message on a different tape is effective to wipeout a posting in the posting panel. Associated with each of the tape reperforators is a. tape feed mechanism, a distributor and a plurality of decoder units, one for each character of the flight data, such as the diiferent digits of flight number, denominations of time and altitude.

The control panel of Fig. 1 also includes indication lamps NPK, PK and WOK, which lamps are normally illuminated. The lamp NPK is eX tinguished whenever a posting or wipe-out operation (either manual or automatic) fails to be completed within a limited time. The lamp PK is extinguished whenever an automatic posting operation fails to be completed within a limited time after its initiation or the punched record of a new schedule being posted includes an improper number of codes; the lamp WOK is similarly controlled so as to be extinguished if an automatic wipe-out operation is not completed within a limited time after its initiation or if the message recorded on the tape includes an improper number of codes. Whenever one of these indicator lamps is extinguished, an audible signal is given to draw the operators attention to such fact; but this audible signal may be stopped if the operator s desires by actuation of the silencing lever or stay-where-put key SIL. This lever or key SIL is provided so that in the event of some failure being indicated, the audible signal may be silenced until after the fault in the system has been located and eliminated, after which the lever SIL is restored to its normal condition. If the fault indicated by one of the lamps and by the audible signal is immediately appar-.

ent, the operation of clear-out button COB will cause the restoration of the ystem to a normal condition in which the indicator lamps are reilluminated and the audible signal is silenced without operation of lever SIL.

' The system organization includes various other devices and relays which are more conveniently considered in discussing typical operations of the system.

General operation It can be appreciated that a system of this character operates differently in detail respects for the large number of different combinations of figures for flight data, the number and order of posting and wipe-out operations for the different flights from time to time, and other varyerations will serve to make clear how the system will operate for various other conditions of posting, wipe-out, and the like for other flight numbers, times, etc.

Manual posting.--For the purpose of explaining the operation of positioning the indicators of a selected space in the posting panel, in accordance with the data for some flight to be posted, it is convenient to assume that the operator receives by telephone from some point, or by radio from the pilot of a flight the information for the posting to be made. The operator first positions the flight number, time and altitude setting dials DFI, DFZ, etc. on the control board in Figs. 1, 2B and 2C to conform with the data to be posted, and then actuates the posting button PB. The resultant sequence of relay operations is indicated in the sequence diagram Fig. 6A; and the circuits involved in this operation will now be explained in detail with reference to Figs. 2A, 2B and 2C.

The actuation of the button PB establishes an energizing circuit for the relay OP in Fig. 2A which may be traced from through button PB, back contact 48 of relay WOR, relay OP, back contacts 49 and 50 of relays l-STR. and S'I'R, back contact 5| of completion relay CP, clear out button COB, and back contact 52 of sequencing relay SQ, to

The relay OP closes its front contact 54 to provide a stick or looking circuit independently of the button PB.

The energization of the relay OP opens at its back contact 56 a circuit for a slow-releasing relay SL readily traced from through back contact 55 of relay ADP and back'contact 56 of relay OP; and after the release time for the relay SL, during which certain other operations may occur as later described, the relay OPR is energized by a circuit from through back contact 55 of relay AOP, front contact 56 of relay OP, back contact 51 of relay SL, relay OPR, to

The energization of relay OP and closure of its front contacts 60 and 6! connects to the flight number setting dials DFI and DF2 in Fig. 2B, and the energization of relay CPR and closure of its front contacts 62 through 66 connects to the time and altitude setting dials DTI, DT2, DT3, DT4, DA in Fig. 23, thereby rendering the existing positions of these setting dials effective to determine the energization of the associated groups of control buses.

The energization of relay OP completes a circuit for vacant space selection which may be traced from through back contact 68 of completion relay CP, front contact 69 of relay OPR, back contact 10 of the same flight relay SF, wire H, cut out switch IK, to the empty-full contact 38 of an indicator for the first space. Assuming this space to be vacant, so that the empty-full contact 38 is in the position shown, current may then flow over wire 12 through the Winding of the space relay ISP for this space to The energization of the space relay I'SP for the first space assumed to be empty, closes its front contact 14 to energize a, relay IFV over an obvious circuit, which closes its front contact 15 to provide a stick circuit for the space relay ISP to space stick bus SS and maintain relay ISP energized independently of the empty-full contact 38 and the back contact 10 of the same flight relay SF because bus SS is directly connected to from contact 69 by wire 43L The closure of front contacts 16 and ll of the space relay ISP connects through .the flight number correspondence .relays IFCRI and IFCRZ to'thelposition contactsof these indicating units. Similarly, the energization of the .relay, .IFVand closure of its front contacts 80 throughM connects (+)v to the correspondence relays l'I.CR|, lTCRZ. etc. for the-four denominations of. time and also to the correspondence relay IACR .for theialtitude indicator.

The energization of the flight vertification relay IFV and closure of its front contact 86 also permits energizationof the same flight relay vSF by a circuit from back contact 85 of relay. GP. relay SE, wire 434, same ,flight panel bus, SFB, front contact 86 of relay. lFV, to but the energizationof the same flight. relay SF ,undezathese conditions and. at this time does not affect the-operation under consideration of makinga posting in vaselected vacantspace, but is significant in connection .with posting revised flight schedules and the wipe-out operation, as later explained.

v-Also,- the closure ofthe front. contactSll of .the space relay ESP connects. .the master pulsing bus? to the space pulsing bus 9| for the space-inquestion, which is connectedtothe operating, magnets OM. of each of: the. indicators through, back contacts .of the associated correspondence relays, such as the back contact 92 for the correspondence relay IFCRifor thefilrstdigit of' flight number.

Thus, the operating magnets OM- for. each of the indicators in the particular selected-space underconsideration are setrinto operation .to move their indicator drums from the blankpositions clockwise as shown, and actuate :their position contacts. to connect the=associated :correspondence relays .IFCRI, .I-FCRZ, etc. in turn to the-different numbered. buses of the associated group of control buses.

this. connection, it willbe. noted: that the busJl32 extending from the blankpositions of the indicators in the space in question ishconnected. through front contact-8lof the. space relay. l SP to .a blank 'positionlbus BP for the panel, .which in turn is normally. connected through back contacts. 88 and89 of relays OP and AOPjto but the circuit.thusi-provided is opened ,by the energization of the relay. ,0? during the manual posting operation under consideration, so that the correspondence relays 'l'FCRL. IFCRZ, etc. for these indicators cannot be energized with the indicators in .the initial or blank positions. In this way, the indicators are caused tobevmo ed tothe particular posi- 'tijons called for. by the energization ofthecontrollb'uses.

,Assume, for example, that the first digitof the flight number to be posted is Land the setting 'dial ,DFI is in theposition 1 to i-connect through front contacttfl of relay OR to the control, bus I of the group-of busesrbelonging; to-said first-digit ofthe flightnumber. -Whenthe indicator in the firstspace hasbeenoperated by its operatin magnet OM. to the positioneto .display ,l,..a,circuit to energize thecorrespondence relay IFCRI is established, thereby energizing this relay toopen at its back contact 92, the connection-between, its operating-magnet OM and the space pulsingbus 9|, so that this-indicator stops inthe. position corresponding with the position of thesetting dial DFI This energization circuit :for the correspondence relay IFORI in the case just assumed:;may'-be traced from through front contact'lti of 12 space relay. ISP, relay: IFCRI, indicatorposition 1,. control bus I, settingdial DFI in position 1, wire 93, front contact 60 of relay OP, to

Itcan. be seen that if the indicator should ,failtomove, or. if there is a had contact or broken Wire. involved in the control bus circuit for this position 1, the correspondence relay ,iFCRl is not energized, and stepping operation of the indicator continues.

The operation just described in detail for the first digit of the flight number is characteristic of'operations of all of the. indicators, which are moved in a similar manner to the particular position called for by the energizationrof the associated control bus, whereupon the indicator is stopped by energization of its associated correspondence relay.

After all of theindicators for this space in question have operated properly to the-positions called for, so that all of the correspondence relays IFCRI and IFCRZ, ITCRI, etc., are energized, a completion circuit is established which may be. traced from in Fig. 2C through the front contacts 95 through Ill-I in series of the .correspondence relays IACR, lTCR -l, etc. to a completion bus CB for the panel, thence over wire I02, completion relay CF, to

,The. energization of the completion relay CP upon completion of the positioning of the indicators intheirnew positions and the opening of its back contact 5| opens the stick circuit before described for the relay OP. The opening of the back contact 58; of this relay CP opens the stick circuit of space relay ISP, and back contact opens the energizingcircuit for the same flight relay SF.

-The release of the .relay OP acts to open its frontv contacts 60 and GI and disconnect from the flight number setting dials, while the release of the space'relay ISP acts to open its frontcontacts- Hand 11 to disconnect from the flight number correspondence relays .IFCRI and IFCRZ, which deenergizes these correspondence relays to open their front contacts I00 and 10 land; release the completion relay CP.

The release of the space relay ISP opens at its front contact 99 the connection from the master pulsing bus P to the pulsing bus 9| for the space in question, prior to the release of the correspondence relays IFCRI and I FCRZ, so that .there-is-nooperation; of the associated operating magnets OM-to disturb the position of these indicators. The release of the relay OPR following the release of relay OP disconnects from the time; and altitude setting dials to release the correspondence relays I 'I'RCI ITRCZ, etc., for the time and altitude indicators; and these correspondence relays .drop at about the same time that relay CP drops and the relay IFV is released due to the opening of the front contacts I03 and H34 of the correspondence relays IFCRI and IFCR2, as indicated in the sequence diagram Thus, the various relays operated'during this posting operation are restored to their normal conditionssh'own, ready for a subsequent operation; and the indicators in the selected space are left in theiroperated positions to display the desired flight data. These indicators are held in top space in the particular arrangement shown, is already filled with a flight schedule, the emptyfull contact 38 of this space is moved from the position shown to the dotted line position; and referring to Fig. 7, current then flows through this empty-full contact 38 in its dotted line 'position through a back contact I of the space relay I SP, and wire I06 to the emergency switch 2K and empty-full contact 38a for the next space below. If this space is empty, then the relay 2SP is energized, but if this space should also be full, the vacant space selecting circuit continues in a similar way to the next space below, and so on, until a vacant space is reached and the space relay for that space is energized.

Thus, the first vacant space in the posting panel is automatically selected to receive the new flight schedule data; and the indicators of that space alone are those which are operated in accordance with the existing energization of the control buses. As illustrated, this vacant space selection operates from the top down, but it can be readily seen that the feed connections may be changed to provide for vacant space selection from the bottom up.

It will be noted that this scheme of vacant space selection is entirely automatic, and does not require any manipulation on the part of the operator to pick a space into which the schedule data shall be posted. It should perhaps be pointed out that, if the flight schedules are posted and wiped out properly in the order of their scheduled times, these schedules may appear in proper time sequence in the posting panel to a limited extent, that is, in groups. For example, starting with the posting panel empty, the first schedules posted prior to any wipe-out will appear in the spaces in the order posted, and will be in time sequence if the schedules are posted in the order of their scheduled times. However, as soon as one of these schedules, presumably the one with the earliest schedule of time, has been wiped out, a vacant space exists and the next new schedule will be routed into this vacant space by the vacant space selecting circuit. If the wipeouts should then occur as fast as new schedules are posted, a new group of schedules in time sequence might appear in the posting panel.

However, it is contemplated that the forecasts of scheduled times of arrival of flights will be known or reported to the central office by Teletype facilities, from time to time as and when such forecasts are made, and probably in a quite different order than the actual time sequence of these forecasted or scheduled times. Also, there is not necessarily any relation in the rate at which flights are disposed of and their posted schedules wiped out, and the rate at which new time schedules may be determined or received at the central office. Consequently, the schedules posted in the posting panel automatically on some arbitrary basis, such as the selection of the first vacant space as here proposed, will ordi narily appear in an indiscriminate and variable order with respect to the scheduled times; and since it is tiresome and diflicult to pick out. by visual inspection from such a display of flight data the-particular flight or flights arriving first and requiring attention, the time sequencing feature of this invention is of great aid to an operator.

Automatic revision of posting.-It may happen that after a given flight has been reported, and posted to arrive at a certain time, it becomes necessary for some reason to change this scheduled time, or perhaps the altitude. In accordance with this invention, the posting of a revision of an existing schedule for some flight is made entirely automatically. This not only avoids the need for a special wipe-out control, as later explained, to eliminate the old data when the revised schedule is to be posted, but also assures that there will not be more than one schedule in the posting panel for a given flight number.

Considering this situation where the data set up on the setting dials represents a revision of the schedule for the same flight already having its data posted, assume for purposes 01 explanation that the flight number setting dials DFI and DFZ are set to energize the control buses I for both groups of flight number buses to correspond with a flight number 11, and that the same flight number 11 is posted in the first space shown in Figs. 23 and 29, so that the flight number indicators for this space are in position 1.

When the relay OP is energized by actuation of the posting button PB, as previously explained, and the closure of its front contacts 60 and BI connects to the flight number setting dials, the closure of fronticontact I09 of relay OP also supplies through wire 433 to the test bus TB and allows current to flow through a rectifier H0, back contact 16 of space relay ISP, correspondence relay IFCRI for the first digit of flight number through the corresponding position contacts assumed to be in position 1, control bus I, through the setting dial DFI in position 1, wire 93 and front contact 60 of relay OP, to thereby energizing relay IFCRI, since the first digit of the flight number posted in the space in question corresponds with the first digit set up on the setting dials.

This energization of relay IFCRI closes its front contact H 2 to connect to the correspondence relay IFCRZ for the second digit of the flight number, and if the position of this indicator corresponds with that of the setting dials, as in the case assumed, this other correspondence relay IFCRZ is also energized. Simultaneous energization of both of the flight number correspondence relays IFCRI and |FCR2 closes a circuit through their front contacts I03 and H14 to energize the flight verification relay IFV, thereby closing its front contact 86 to energize the same flight relay SF over the circuit including the same flight bus SFB, wire 434 and back contact of relay CP.

Since the unit for each posting space is similar to the one shown, it will be apparent that the test bus TB provides positive energy for the first digit flight number correspondence relay of each posting space. Thus, regardless of the particular posting space in which the same flight number is posted, the flight verification relay FV for that space is picked up. With this organization it is apparent that should several posting spaces have the same number in the first digit of flight number, the correspondence relay FCRI for these posting spaces would be picked up and supply positive energy to the correspondence relay F'CR2 for the corresponding second digit of flight number. But since it is assumed that only one flight will be given any particular number it will be apparent that the correspondence relay F'CRZ for the second digit will be energized for only that particular posting space having the same flight number as that set up on the flight number setting dials DFI and DF2. For this reason the flight verification relay FV will b picked up in themanner described for only the: posting space having the same flight number.

This operation of checking .the postings to determineif the same flight number appearing on the setting dials is already set up in some posting space, occurs while the relay SL is releasing and the energization of the relay SF opens at itsback contact and the vacant space selecting circuit before the relay OPR is energizedto close its front contact 69 and apply energy to this circuit. Thus-ii the same flight number appears in an existing posting space, the vacant space selecting circuit is opened prior to the energizat-ion, of a space relay for the next vacant space. The relay, however, is energized at this time for the space having posted therein the same flight number, which in the case assumed is relay IFV for the first space, and the closureof its front contact f 75 permits energization of the corresponding' space relay such as lSP as soon' as relaySL releases and efiects the picking up of relay OPR, to close front contact 69.

The energization of the space relay in which the same flight is posted, such as the relay ISP, causes operation of the indicators of that space to correspond With the setting of the .setting' dials, so that the schedule posted in such posting space 'is' revised accordingly.

In other words, in accordance with this invention, when a posting operation is initiated, there is first a period during which the existing schedules are checked to determineif data for the same flight number has been previously posted; and if such is the case, the vacant space selection is rendered ineflective, and the particular space including such data is selected as the one to have its indicators operated. If there is no existing posting for the same flight number, then after the relatively short test period, the vacant space selecting circuit acts to route the new flight schedule to the first vacant space.

Automatic posting of a new or revised flight schedule will result in a similar way upon energization of a relay AOP in connection with receiving and decoding Teletype posting messages, as more conveniently explained later.

.Manuwl wipe-out.When a "flight having schedule data posted in some space of the posting panel has landed or is otherwise disposed of, this data is no longer of interest to the operator, and should be removed from the posting panel by an operation conveniently termed a wipe-out operation. This wipe-out operation involves selection of the particular space in which the posting to be wiped out appears, and then causing the indicators for this particular space to be operated to their blank. positions.

Although this wipe-out operation is performed in the organization disclosed, either in'response to the manual setting of flightnumber dials and actuation of a wipe-out button, or automatically in re'sponseto a wipe-out message received over a Teletypesystem, it is convenient to limit consideration at this point to the manual Wipe-out operation.

For a manual wipe-out operation, the flight number for the schedule data to be wiped out is set up manually by manipulation of suitable flight number setting dials or a key set device; and for reasons already noted, it is considered preferable to employ a separate set of flight number setting dials WDFI and. WDFZ for this purpose, although, it should be understood that the same means for setting up a flight number desig- 16 nation' may be -employed for-both posting: and wipe-:out operation.

Whenithese' flight number setting dials-WDF-l and WDFZ for wipe-out have been positioned', which maybe 1 done by a separate 'operator at any-convenient location, this operator actuates a push button WOB to energize a wipe-out relay WOR inFigL2A, subject to an interlock against conflicting operations, by a circuit which maybe traced from button WOB, relay Wort-back contact H5 of relay O-P, back contacts 49 and-=50 of relays ISTR and.STR; involved in: automatic posting and Wipe-out operations, ba'ck' contact 5| of a completion relay CP, normally closed "contact of a cancel :or clear-out button COB and-back contact 52 of a sequence relay SQ-to Fig. 6B shows the resultant rela-y'operations. In the first place, theenergiZationLof relay WOR closes its front contact I IE to provide a sti'ck ci'rsuit for: maintaining it energized independently of the? push button WOB.

The .energization of the relay-'WOR-also'connects through its front contacts l H; H8and back contacts H9 and of the-same' flight relay SF to the flight number settingdialsWDFl and WDFZ for wipe-out; and at the same time the closure of the front contact I22 of :ther'elay WOR connects (-1-) through wire 433 to the test bus'TB. Assuming for the purposes of explanation that the posting 'for a flight number ll appears in the posting space illustrated, so that the flight number indicators are setting in position-1, the same'as the existing positions of the iflight number setting dials, 'upon energizationiof the relay WOR, the correspondence relay? lFCRl for the first digit of the flight number is energized over a circuit from through front contact I22 of relay WOR, Wire 433, test bus TB; rectifier llil, back contact 16 of space relay I SP, relay IFCRl, indicator in positionil, controlfbu's I, setting =dial' WDFI in position 1, front contact I is of relay WOR, back contact 120 of relay- 8F, to

A correspondence relay for the flrst'digit of the flight number, such as IFCRI, may also be en ergized for other posting spaces having-flight numbers'with the same first digit; and for each of these other spaces, as well asior the space illustrated, in which the flight number to be wiped out is assumed to be located, the energizetion of the corresp'ondence'relay' such as :IFCR'I and closure of its front contact H2 connects to the correspondence relay,'such'as relay lFCRE, for the second digit of the flight'number. If this second digit of the flight number as posted, as well as the first digit, corresponds with" that set up on' the setting dials, which is true only for the. schedule data to be wiped out, then the correspondence relay such as IFCRZis energized over a circuit similar to that described for the energization of the correspondence relay IFCRI for the first digit of the flight number. Thus, both correspondence relays; suchztas: JFCR'I and IFCRZ, for the particular space containingthe posting to be wiped'out are energized'toclose their front contacts H33 and "M -and energize the flight verification relay, such as relay IFV, for that particular space. The sameiprinciples of selection may be carried out for as many 'flight number digits as desired.

The energization of the flight verificationrelay, such as relay IFV, for;the particularzposting space containing the data to be wiped'out, and closure of its front contact 86 causesenergization of the same flight relay sFto 'cl'ose its 

